Now if your lab partner determined that there were 3.824 x 1023 atoms of H in an unknown sample of C2H4Cl2, how many milligrams would the unknown sample weigh?
divide that number by 4, that will be the number of molecules.
mass=numbermolecules/avagnumber * molmass of the molecle (in grams)
To find the weight of the unknown sample in milligrams, you need to use the given information about the number of atoms of H, as well as the molar mass of C2H4Cl2. Here's how you can calculate it:
1. Determine the molar mass of C2H4Cl2:
- Carbon (C) has a molar mass of 12.01 g/mol.
- Hydrogen (H) has a molar mass of 1.01 g/mol.
- Chlorine (Cl) has a molar mass of 35.45 g/mol.
Multiply each element's molar mass by the number of atoms present in the molecule:
- (2 x C) + (4 x H) + (2 x Cl) = 2(12.01 g/mol) + 4(1.01 g/mol) + 2(35.45 g/mol)
- Simplifying, you find that the molar mass of C2H4Cl2 is 98.96 g/mol.
2. Convert the number of atoms of H to the number of moles:
- The given quantity (3.824 x 10^23 atoms) represents the number of atoms of H in the sample.
- To calculate the number of moles, divide the number of atoms by Avogadro's number (6.022 x 10^23 mol^-1):
3.824 x 10^23 atoms / (6.022 x 10^23 mol^-1) = 0.635 mol (approximately)
3. Calculate the weight of the unknown sample in grams using the molar mass:
- Using the molar mass of C2H4Cl2 from step 1, multiply it by the number of moles calculated in step 2:
0.635 mol x 98.96 g/mol = 62.81 g (approximately)
4. Convert the weight from grams to milligrams:
- Multiply the weight in grams by 1000 to convert it to milligrams:
62.81 g x 1000 mg/g = 62810 mg
Therefore, the unknown sample would weigh approximately 62810 milligrams.